Urgent help - Mini IR sensor with DUET 0.6

I am using DUET 0.6 boards (from Reprap ltd) in 2-3 printers. Previously I was using 4 pin old IR sensor from Reprap ltd.

3 months back, I purchased 3 pin mini IR sensor and started using it. Working without any issues. Differences are quite big.

Last 10 days I was building one CoreXY with 300x300x300. I updated Reprap firmware with 1.18.1. And used the configurator to create config files for CoreXY setup.

All the movements are ok. But I faced a weird issue with the mini IR sensor. When I used it for homing only Z axis, when the bed comes near the sensor, it is showing the value of 465, but it is not homing. I tried with different parameters, different settings, different wires etc. It is not homing.

Then I changed the same sensor to other Cartesian machine (same DUET 0.6 board), it is working.

Only, it is not working with this CoreXY. Then, I used old 4 pin IR sensor with this CoreXY, it is working, but not that accurate.

Please help me in sorting out this mini IR sensor issue. (I have to deliver the machine to the client by tomorrow).

The following are the lines from config file (I am not sure how to attach a file here).

There are two receivers on the board. in analog mode the first one will give an output of 465, this will cause the z motion to slow down. What it is looking for is the second output at about 535. This is the one that should trigger the endstop.

You should be able to trigger these with your hand and see the output with an M119

Your IR sensor will output about 465 which it is approaching trigger height, and about 535 at/below trigger height. At the same time as producing a reading of 535, the red LED on the sensor will turn on. If you don't get 535 even with the nozzle touching the bed, this usually means you have mounted the sensor too high on the hot end. The bottom of the sensor should be no more than 2mm higher than the tip of the nozzle, and preferably about 1.5mm.

In this case, after homing X and Y, I tried to trigger the Z sensor manually. The value of 465 comes, then it triggers at 535. But it is not showing as 'Home Z' is done. In DWC, the 'Home Z' is still in Yellow color. Also, the Z axis is still moving without stopping.

Any coding issue? I am getting Red light glowing properly when I do manual triggering. Even when the machine is switched on the red light is blinking for 4 times.

As suggested by DjDemonD, I changed the value to 450. Luckily it started triggering. But, here and there it is giving errors. I changed the values to 460, 470, 480. At 480 it is not triggering. So, now keeping at 470 only. But still some issues.

I can't see anything in your homez.g or config.g that would cause this.

Please try raising the nozzle some way off the bed. Check that when you hold a piece of paper under the nozzle, the red LED comes on and the Z probe reading jumps to about 535. Then execute G30 to start a single Z probe. When you hold the paper under the nozzle so that the LED comes on, the probing move should stop.

If that works, then Z homing should work if you can get the probe to trigger before it touches the bed. What bed surface are you using? If it is transparent to IR (e.g. glass, PEI, or PrintBite), how thick it is, what is the surface below it?

If I give the above command as it is in config.g, Auto bed compensation is not happening.
So, that I am giving like this:

M558 P1 X0 Y0 Z1 ;H5 F120 T6000 Set Z probe type to unmodulated, the axes for which it is used and the probe + travel speeds. - Here I am disabling after H5
;M557 X15:285 Y15:285 S20 - This line also disabled.

Now when I checked it again, it is working only with the value of 460.
At the value of 460, when I move the paper against the sensor, Z probe value is changing to 465 and becomes red (in DWC). Even at Z homing, if I move the paper, the value changes to 465, becomes red and Z stops.

Whatever other value I use like 470, 480, 500, even 505, for all these values, Z probe value is showing as 465,466 - only green indication is coming on Z probe value (in DWC). The red indication is not at all coming.

Please verify that with the tip of the nozzle touching the white masking tape, the distance between the bottom edge of the sensor and the bed is no more than 2mm. If that's the case, and you are only getting a reading of about 465 and the red LED doesn't illuminate, ask your supplier for a replacement IR sensor. If you bought it direct from me, please provide the invoice number and delivery postcode if you can.

I verified the distance. It is below 2mm only. Red LED in the IR sensor is glowing. But, the red indication in Z probe value in DWC is not coming. It shows only Green indication (for values more than 460). For value of 460, the red indication is coming.

I bought it from DUET3d 6 months ago. But, started using last month only